This is a feature I have been working on for after B5 stable has been officially released. Audio is being routed from the guest VM via the emulated Intel HDA device over the SPICE audio playback channel (not IVSHMEM). The result is flawless audio without having to mess around with hacks like SCREAM.
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https://www.youtube.com/watch?v=uQm8Yw_QP3I